The present invention relates to a device for peeling off a thin film, and particularly relates to a device for peeling off a thin film from a base plate.
A printed circuit board, which is used in electronic equipment such as a computer, includes a wiring pattern made of copper or the like formed on one side or both sides of a electrically insulating base plate.
The printed circuit board is manufactured with a process as follows: A stacked assembly of a photosensitive resin (photoresist) layer and a light-transmissible resin film for protecting the photosensitive resin layer is laminated by heat and pressure on an electroconductive layer formed on an electrically insulating base plate. A wiring pattern film is then overlaid on the stacked assembly. The photosensitive resin layer is exposed to light through the wiring pattern film and the light-transmissible resin film for a prescribed time. The light-transmissible resin film is thereafter peeled off. The photosensitive resin layer exposed to light is then developed so that an etching mask pattern is formed. After that, the unnecessary portion of the electroconductive layer is removed by etching. The remaining photosensitive resin layer is then removed to complete printed circuit board.
In such a process of manufacturing the printed circuit board, a step of peeling off the light-transmissible resin film is required before the photosensitive resin layer exposed to the light is developed. Since the light-transmissible resin film is conventionally manually peeled off and the thickness of the film is small, the operator who performs this operation must be highly skilled in order to avoid damaging or destroying the photosensitive resin layer due to peeling stress concentration or the like. For that reason, it is time-consuming to properly peel off the light-transmissible resin film. Therefore, there is a problem in that the work time for the manufacture of the printed circuit board is long.
In order to solve this problem, an automatic thin film peeling device, as disclosed in commonly assigned Japanese Patent Application No. 23178/86, has been developed. The device functions so that the end of a light-transmissible resin film included in a stacked assembly stuck to a base plate is separated by a needle-like projection pusher and a fluid is blown against the separated portion of the film to automatically peel off the light-transmissible resin film.
However, it is difficult to optimally shape the tip (which is used for separating or pull-raising, i.e., simultaneously pulling and raising, the light-transmissible resin film) of the projection pusher of this automatic thin film peeling device. If the tip of the projection pusher has an acute-angled form, the tip tends to damage the light-transmissible resin film or photosensitive resin layer or stick to an electroconductive layer to thus become incapable of peeling off the light-transmissible resin film. On the other hand, if the tip of the projection pusher has a round form, the tip has a tendency to slip on the light-transmissible resin film, making it difficult to positively pull-raise the film to peel it off. Moreover, if the tip of the projection pusher is shaped as a needle, there is a problem in that the tip cannot surely separate or pull-raise the light-transmissible resin film.
Also, since the needle-shaped projection pusher comes into contact with the printed circuit board, the projection pusher is likely to enter a positioning hole provided in the peripheral portion of the printed circuit board (used to overlay the printed circuit board and a wiring pattern film on each other when the photosensitive resin layer is to be exposed to light). If the projection pusher enters a positioning hole, the pusher cannot separate the light-transmissible resin film. In such a case, not only must the continuous peeling of the film be suspended but also the entire thin film peeling process must be halted. For that reason, there is another problem in that the average time per unit taken to peel off the light-transmissible resin film is likely to be high.